Timing Your Workout Right Could Make You … Smarter

Timing Your Workout Right Could Make You … Smarter

Why you should care

Because you might want to be the smartest and the fittest.

Mind and body, mind and body. We’ve long heard this mantra from yoga studios and meditation centers, but there’s plenty of science behind the idea that exercise benefits your brain — particularly learning and memory — as much as your biceps. But when it comes to retaining new information, just working out might not cut it. Research suggests that timing is important too.

To improve your odds of remembering the material you studied for tomorrow’s exam, or your new coworkers’ names, hit the gym — but maybe not right away. A study published in Current Biology in July found that exercise improved recall when done

4 hours

after learning information, but not immediately after.

Brain imaging also revealed sharper activity patterns in the hippocampus, a region crucial for forming and storing memories, among those who exercised four hours after learning. Researchers led by Guillén Fernández, a professor of cognitive neuroscience at Radboud University in the Netherlands, showed 72 men and women pictures of objects at various locations on a screen. They then measured their baseline memory retention by testing their ability to remember each object’s location. Next, they randomly assigned each participant to three different groups. The first group completed a 35-minute interval training on a stationary bike immediately after the learning task and then watched a three-hour nature documentary before returning to the lab to simply sit on the bike for 35 minutes. The second group did the reverse, undergoing the interval training last, while the third group simply watched the documentary and sat on the bike without exercising for two 35-minute periods.

Forty-eight hours later, the researchers ran the memory test on all the participants again, this time in an MRI scanner to image their brains. Those who had exercised four hours after learning had higher memory retention than those who exercised immediately after learning or who skipped exercise altogether. In fact, there was no difference in memory retention between the immediate exercise and no-exercise groups.

Fernández’s team also analyzed the similarity of hippocampal activity patterns in each group. Our brains store memories as patterns of neural activity. The idea is that clearer, more sharply defined patterns — more stable memories — look similar from one individual to the next. “They are not that random,” Fernández says. “They’re better formed.” On the other hand, blurry activity patterns display more variation. Sure enough, hippocampal activity patterns showed greater similarity among participants in the delayed-exercise group when they answered memory test questions correctly. “Brain pictures are very noisy … very blurry.” With the four-hour delay, “they got sharper.”

But compared to the memory test results, the brain images are tougher to interpret, says Wendy Suzuki, a professor of neural science and psychology at NYU. Fernández’s team didn’t see significant increases in hippocampal activity in the delayed-exercise group. More broadly, the images “just didn’t really give a clear picture of what’s going on” as far as the neurological mechanisms involved. The study also doesn’t establish the optimal time to delay exercise, the researchers wrote in their paper — waiting for less than or more than four hours might even translate to bigger memory improvements. They agree that more research is needed. But overall, Suzuki cites the study as “an important new direction.” Earlier work has typically focused on the effects of exercise right after learning.

Although the study authors aren’t sure how putting off exercise offers an edge, we do know that exercise itself boosts the cascade of neurotransmitters important in memory retention, Fernández says. The delay might allow more time for that cascade to take place. He and his colleagues plan to conduct studies with drugs that target some of the molecules potentially involved to unravel the underlying mechanisms.

Besides exercise, other activities, like sleep, might also help with memory retention. For now, we can say that “there are processes in the brain after learning that determine whether you forget or remember something,” Fernandez says. Regardless of how hard you hit the books, “these processes after are important.”

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